The loss of natural teeth may warrant the use of a partial denture or dental appliance. Some of the factors that influence the decision as to whether a partial denture is required include shrinkage of the gums, reduction or removal of the alveolar process or foundation that partially supports the dental appliance, and loss of molars which reduces the number of abutments available for anchoring and supporting the appliance. Another difficulty is that the few remaining teeth may be mobile.
One form of partial denture is known as a clasp type partial. The partial includes hook like portions that are formed of metal or plastic and extend around individual abutment teeth to support the dental appliance in the mouth. When one or more of the abutment teeth is lost, the dentist may recommend an alternative dental appliance such as that disclosed in U.S. Pat. No. 3,271,858. The dental appliance of the 3,271,858 patent addresses the difficulties involved with developing and using partial dentures with a design that includes a metal lingual section adapted to engage abutment teeth, a first metal frame section extending from one end of the lingual section for supporting replacement teeth and a second metal frame section extending from the other end of the lingual section for supporting replacement teeth. A metal labial bar extends between the first and second frame sections. Plastic replacement tissue material extends around the replacement teeth that are carried by the first and second frame sections. A metal hinge member is disposed at one side of the labial bar and a metal latch member is disposed at the other side of the labial bar. The labial bar is connected to the hinge so as to be swingably movable relative to the abutment teeth. The labial bar includes a hook type catch that engages the latch member to enable the abutment teeth to be firmly clasped between the lingual section and the labial bar.
A disadvantage of the dental appliance of the 3,271,858 patent is that the labial bar, the hinge member and the latch member are formed of metal. Therefore, clasp type partials cannot easily be restored so as to utilize this design. In addition, although a plastic replacement tissue portion may be carried by the metal labial bar, the labial bar is bulky in the patient's mouth, may cause discomfort and is unsightly.